Dehydrated potato processes and products

ABSTRACT

A dehydrated potato product yielding rapidly upon reconstitution pieces resembling pieces of fresh potato suitable for frying, as for instance hash brown potatoes, formed by preparing an aqueous dough of about 23 percent solids, not less than about 80 percent of which are undamaged potato cells and the balance of which includes conventional additives and not less than about 6 percent extracellular starch in a form to provide sufficient soluble edible adhesive, forming pieces of the desired size, and drying the pieces to a moisture content of about 71/2 percent.

This application is a continuation of our copending application, Ser.No. 655,746 filed July 25, 1967, and we claim the priority of saidapplication. .[.The priority of common subject matter disclosed in ourearlier application, Ser. No. 547,195 filed on May 3, 1966, pending onJuly 25, 1967, mentioned in Ser. No. 655,746 and abandoned on Dec. 9,1968, is also claimed..].

This invention relates to a novel dehydrated potato product and aprocess for producing the same, involving a specific intermediate mixform. The intermediate and the dehydrated end products are composedessentially of debris-free cooked potato flesh containing someadditives, flavorings or other components, singly or in appropriatecombination. The intermediate is given a higher solids-to-moisture ratiothan found in the normally cooked potato flesh by addition of undamageddehydrated potato cells and is used to form a sheet from which piecesare cut preparatory to drying for producing as end products dehydratedsubstitutes for pieces of dehydrated natural potato for use in makingpan fried and hash brown potato dishes.

Although many dehydrated potato products such as potato granules andpotato flakes have been received well and are produced commercially on alarge scale, similar widespread use has not been achieved by slicedpotatoes and diced potatoes. Slices and dice require prolongedrehydration and are therefore not "instant" and do not have the requiredconvenience factor. Attempts have been made to shorten the preparationtime by drying thinner pieces and more recently by explosion puffing andirradiation to create a more porous structure which is more permeable tothe rehydrating solution. Although this has resulted in improvedproducts, there is still a need for dehydrated potato pieces which canbe prepared completely in a few minutes.

It is a purpose of this invention to describe a process for producinglarge potato pieces which can be rehydrated and prepared as pan friedpotatoes or hash brown potatoes in a fraction of the time required forconventionally dried pieces of the same size.

It is a further object of this invention to produce such potato piecesfree of dark spots, eyes, or blemishes which are common defects inpotato pieces described in prior art.

It is a further object to produce potato pieces suitable for pan friesor hash browns with flavor and color stability superior to that ofconventionally dried potato slices made from intact potatoes.

It is a further object of this invention to produce dehydrated potatopieces which can be used interchangeably with conventional pieces of thesame dimensions but with added convenience and superior performance.

When using raw potatoes as starting material, our process comprises thenormal preparation step of producing a cooked potato or potato piece.From this we produce a debris-free slurry or about 17 percent solids asdescribed in copending application, Ser. No. 222,538, assigned toAmerican Potato Company as is this present application. Although weprefer to produce debris-free cooked potato flesh in this manner, it isobvious that the same result can be obtained following complete removalof skin, eyes, and defective portions by costly mechanical and/or manualtrimming. The solids content of the slurry is then increased to about22-25 percent by partial dewatering, addition of dehydrated instantpotato, or both. Additives such as antioxidants sulfite salts, calciumsalts, sugar, starch or other binders are added as required to controlstability, color, and texture. This thickened slurry or mix is nowcomparable in consistency to a very dry mashed potato. By eliminatingprecooking and cooling of the potato prior to cooking and by adjustingthe slurrying procedure at least a portion of the required adhesivecharacter is obtained from the controlled rupture of a small fraction ofthe potato cells.

In another application of our invention, the debris-free potato mix ismade by reconstituting debris-free dehydrated potato products such aspotato granules or potato flakes, which in commercial form alreadycontain the desired additives. Any combination of potato solids whetherfrom a freshly cooked source or from a dehydrated source can be used inour process by preparing a mix of the proper moisture and containing theproper additives.

We have found several means of obtaining the controlled amount ofadhesion which is necessary in the mix. In our early test work, asdisclosed in our original application, Ser. No. 547,195, filed May 3,1966, a satisfactory product resulted from our process if product piecesize and rehydration time and temperature were controlled closely. Wehave now developed improved processes which are not sensitive to changesin preparation techniques and which resist sloughing even whenoverrehydrated or when rehydrated in very hot water.

In these improved processes, the adhesive force necessary to result inpermanently agglomerated, previously separated potato cells is obtainedby a heat treatment step which gelatinizes raw starches uniformlydispersed in the dough thus forming a binding gel structure which ismaintained in the dough throughout the process.

One example of an improved process for producing hash brown pieces andusing potato granules as the sole source of potato solids, is asfollows:

330 grams of commercial potato granules are mixed uniformly with 30grams of raw corn starch. This mix is then added uniformly to 1,170 ml.of water heated to 185° F. in a Hobart mixer operated at low speed for2-3 minutes to form a homogeneous dough of about 22% solids. The doughis then extruded in strips about one-eighth inch by one-fourth inch incross section and of any length onto a screen. The extruded dough isthen steamed for about 10 minutes on the screen. The heat-treated stripsare then dried, still on the screen, at about 180°-200° F. for about 3-4hours to reduce the moisture content to about 71/2 percent.

An alternate improved process has been also developed in which the heattreatment step to gelatinize the raw starch is accomplished before thedough is extruded. In this application, the heat-treated dough mix mustbe kept hot until extrusion is completed.

When the end product desired in an instant 1/8-inch potato slicesuitable for pan frying, pieces of the desired slice size are formedfrom the hot sheeted mix. These pieces are then predried out of contactwith one another to a moisture content of about 65 percent by subjectingthe individual pieces to air at about 300° F. for about 5-6 minutes. Anyother set of conditions which gives this moisture reduction withoutdamage would be acceptable. The purpose of this step is to predry thesurfaces of the pieces so they do not adhere to each other in finaldrying. The final drying step immediately follows before diffusion ofmoisture to the surface of the pieces can create any stickiness. Thefinal drying step is normally conducted with the pieces in severallayers on a continuous perforated belt dryer using air at about 200° F.until the moisture content is reduced to about 6 to 7 percent.

In the development of our novel improved processes, several facts weredisclosed by our research:

We found that all raw starches tested were effective adhesive agents,but that raw corn starch resulted in finished products with superiorrehydration and handling attributes.

We further found that effective starch gel formation in the doughrequires a minimum heat treatment temperature of about 190° F. In testswhere dough was heated to only 170° F., no beneficial result was found.Another important discovery of our research was that the temperature atwhich the dough is dried is critical. If excessive drying temperaturesare employed, the outer layer of the extruded pieces dries too quicklycausing case hardening which results in puffed pieces which sloughundesirably when reconstituted.

The starch added for adhesion must be in the raw or ungelatinized statewhen mixed into the dough. A cooked or gelatinized starch ingredientdoes not form the proper gel distribution. The most desired quantity ofraw starch ranges from 6-20 percent. With less than 6 percent thereconstituted product sloughs excessively. With more than 20 percent theend product has less potato flavor, less desirable browning, and has anundesirable tough or rubbery texture. Our tests with corn starch andcommercial potato granules have shown that about 9 percent starch and 91percent granules is optimum.

Mixing of the heat-treated dough can be damaging to the starch gelstructure. We have found that if mixing is required, the dough must bekept hot during this operation. If the dough cools before the finish ofmixing or before extrusion, the gel structure is disrupted and theadvantages of our process are decreased.

Although the drying step can be started immediately following the heattreatment of extruded pieces, even more resistance to sloughing can beobtained by allowing the pieces to cool thereby creating a more stablegel structure before dehydration. As mentioned, satisfactory productscan be made from freshly cooked potatoes or from granules or flakes. Itis obvious to anyone skilled in the art that mixtures of any of thesepotato solids sources can also be utilized.

Although we prefer a solid content of the dough of about 23-25 percent,a range from 17-50 percent gives useful results. If the solids contentis appreciably below 20 percent, physical handling becomes difficult. Ifthe solids of the dough is appreciably above 25 percent, the endproducts are more susceptible to sloughing upon reconstitution.

The products of our novel processes have great flexibility in use. Thefollowing conditions of rehydration all give properly reconstituted hashbrown pieces which can be pan fried in about 4 minutes at about 275° F.

Cold water soaking for about 15-30 minutes.

140° F. water soaking for about 5-10 minutes.

200° F. water soaking for about 3-5 minutes.

The products of our invention can be subjected to prolonged rehydrationwithout undesirable sloughing; however, any liquid absorbed in excess of1.5-2.0 times the dry weight would have to be boiled away before fryingtakes place.

The excellent rehydration characteristics allow simultaneous rehydrationand frying in a single pan. An excellent one-pan recipe for hash brownsis as follows:

125 grams of the dehydrated hash browns are mixed with salt, fat, and 1to 11/4 cups of water. When the mix is heated, an excellent hash brownpotato with desirable piece identity can be finished in about 10-14minutes.

There are several advantages in the products of our invention overpresently available products. The dehydration of a conventional blanchedpotato piece requires many hours and we have found by using sensitivegas chromatographic techniques that rancidity actually develops beforethe piece reaches the required finished moisture content. Although thisrancidity is not strongly objected to by a majority of users, it may beat least partially responsible for limited usage of these products. Inour process, if freshly cooked potatoes are used, they are immediatelymixed with the conventional protective additives which are incorporateduniformly and contact and protect all parts of the mix.

Storage of the final dried products demonstrates the stability of theproducts of our invention as evidenced by low hexanal formation.

A further advantage is gained from the fact that the products of ourinvention are made from a debris-free cooked potato slurry or fromdebris-free dehydrated products. The end products are therefore free ofblemishes, eyes, fibers, and other discolored pieces which would have tobe mechanically or manually sorted from conventional dehydrated potatopieces.

The permeability which is attained by the permanent agglomeration ofpreviously separated potato cells allows ready penetration ofreconstitution liquid in contrast to conventional dehydrated pieceswhich have a tough horny exterior which requires prolonged soaking forproper rehydration. When the products of our invention are to bereconstituted for pan fries or hash browns, it is not necessary to bringabout complete rehydration, since much of this water would simply bereevaporated as frying takes place.

A further advantage of the products of our invention is the ability toincorporate sugars in desired concentration to the mix so that the colorcan be controlled in the fried end product. It is well known that freshpotatoes contain varying amounts of sugar depending upon growing andstorage conditions. It is the subject of many patents to control thesugar content of fresh potato pieces by complicated processing steps.

We claim:
 1. A process for producing a reconstituted dehydrated cookedpotato strip or piece suitable for use, without loss of piece identity,in the preparation of dishes as a substitute for a like strip or pieceof natural cooked potato comprising the steps of:a. producing an aqueousdough with a solids content on the order of 25 percent, said solidscomprising not less than 80 percent undamaged separated previouslydehydrated cooked potato cells and a maximum of 20 percent ungelatinizedraw starch added in an amount sufficient after subsequent gelatinizationto give the required adhesive character to the dough to impart to theeventual dehydrated strip or piece a texture to allow reconstitution andpan frying without loss of piece identity; b. subjecting said dough to atemperature sufficient to gelatinize the ungelatinized starch withoutdrying; c. forming said heat-treated dough while still hot into piecesor strips about one-eighth to one-fourth inch in thickness, suitable foreventual dish preparation; d. predrying said pieces or strips out ofcontact with one another to remove the surface moisture to prevent themfrom adhering to one another; e. finally drying said pieces or stripsimmediately following the predrying to prevent diffusion of moisture totheir surface to a moisture content on the order of 71/2 percent; and f.reconstituting said pieces with water without loss of piece identity foruse in dish preparation.
 2. A process for providing a reconstituteddehydrated cooked potato strip or piece suitable for use, without lossof identity, in the preparation of dishes as a substitute for a likestrip or piece of natural cooked potato comprising the steps of:a.producing an aqueous dough of 17 to 50 percent solids, by mixing notless than 80 percent undamaged separated previously dehydrated cookedpotato solids with ungelatinized starch to give total extra cellular rawstarch content of 6 to 20 percent of the total solids content; b.subjecting said dough to a temperature sufficient to gelatinize the rawstarch without drying; c. forming said heat-treated dough while stillhot into pieces or strips about one-eighth by one-fourth inch inthickness, suitable for eventual dish preparation; d. predrying saidpieces or strips out of contact with one another to remove the surfacemoisture to prevent them from adhering to one another, e. finally dryingsaid pieces or strips, immediately following the predrying to preventdiffusion of moisture to their surface to a moisture content of theorder of 71/2 percent; and f. reconstituting said pieces with waterwithout loss of piece identity for use in dish preparation.
 3. A processfor producing a reconstituted dehydrated cooked potato strip or piecesuitable for use, without loss of piece identity, in the preparation ofdishes as a substitute for a like strip or piece of natural cookedpotato comprising the steps of:a. producing an aqueous dough containingon the order of 25 percent solids consisting of undamaged separatedpreviously dehydrated potato granules and a quantity of added rawstarch, said starch being in the range of from about 6 to about 9percent of the solids; b. subjecting said dough to a temperaturesufficient to gelatinize the ungelatinized starch without drying; c.forming said heat-treated dough while still hot into pieces or stripssuitable for dish preparation, about one-eighth to one-fourth inch incross section; d. predrying said pieces or strips out of contact withone another to remove the surface moisture to prevent them from adheringto one another; e. finally drying said pieces or strips, immediatelyfollowing the predrying to prevent diffusion of moisture to theirsurface to a moisture content on the order of 71/2 percent, and f.reconstituting said pieces with water without loss of piece identity foruse in dish preparation.
 4. A process for producing a reconstituted andfried, previously dehydrated, potato strip comprising the steps of:a.admixing undamaged separated previously dehydrated potato granules withraw starch, said starch being in the range of about 6 to 9 percent; b.producing a dough of about 25 percent solids with said mixture; c.subjecting said dough to a temperature sufficient to gelatinize theungelatinized starch without drying; d. forming said heat-treated pieceswhile still hot into pieces about one-eighth to one-fourth inch inthickness suitable for rehydration and frying; e. predrying said piecesout of contact with one another to remove the surface moisture toprevent them from adhering one to another; f. finally drying said piecesby following the predrying to prevent diffusion of the moisture to theirsurface, to a moisture content on the order of 71/2 percent; g.reconstituting said pieces with water without loss of piece identity;and h. frying said rehydrated pieces to produce permanently agglomeratedpreviously separated and dehydrated intact hash brown potato.
 5. Aprocess for producing a reconstituted dehydrated cooked potato strip orpiece suitable for use without loss of piece identity in the preparationof dishes as a substitute for a like strip or piece of natural cookedpotato comprising the steps of:a. producing an aqueous dough with asolids content on the order of 25 percent, said solids comprising notless than 80 percent undamaged separated previously dehydrated cookedpotato cells and a maximum of 20 percent ungelatinized raw starch addedin an amount sufficient after subsequent gelatinization to give therequired adhesive character to the dough to impart to the eventualdehydrated strip or piece a texture to allow reconstitution and panfrying without loss of piece identity; b. forming said dough into piecesor strips about one-eighth to one-fourth inch thick, suitable foreventual dish preparation; c. subjecting said pieces or strips to atemperature sufficient to gelatinize the ungelatinized starch withoutdrying; d. predrying said pieces or strips out of contact with oneanother to remove the surface moisture to prevent them from adhering toone another; e. finally drying said pieces or strips immediatelyfollowing the predrying to prevent diffusion of moisture to theirsurface to a moisture content on the order of 71/2 percent; and f.reconstituting said pieces with water without loss of piece identity foruse in dish preparation.
 6. A process for producing a reconstituteddehydrated cooked potato strip or piece suitable for use, without lossof piece identity, in the preparation of dishes as a substitute for alike strip or piece of natural cooked potato comprising the steps of:a.producing an aqueous dough of 17 to 50 percent solids, by mixing notless than 80 percent undamaged separated previously dehydrated cookedpotato solids with ungelatinized starch to give total extra cellular rawstarch content of 6 to 20 percent of the total solids content; b.forming said dough into pieces or strips about one-eighth to one-fourthinch thick, suitable for eventual dish preparation; c. subjecting saidpieces or strips to a temperature sufficient to gelatinize theungelatinized starch without drying; d. predrying said pieces or stripsout of contact with one another to remove the surface moisture toprevent them from adhering to one another; e. finally drying said piecesor strips, immediately following the predrying to prevent diffusion ofmoisture to their surface to a moisture content on the order of 71/2percent; and f. reconstituting said pieces with water without loss ofpiece identity for use in dish preparation.
 7. A process for producing areconstituted dehydrated cooked potato strip or piece suitable for use,without loss of piece identity, in the preparation of dishes as asubstitute for a like strip or piece of natural cooked potato comprisingthe steps of:a. producing an aqueous dough containing on the order of 25percent solids consisting of undamaged separated previously dehydratedpotato granules and a quantity of added raw starch, said starch being inthe range of from about 6 to about 9 percent of the solids; b. formingsaid dough into pieces or strips about one-eighth to one-fourth inchthick, suitable for eventual dish preparation; c. subjecting said piecesor strips to a temperature sufficient to gelatinize the ungelatinizedstarch without drying; d. predrying said pieces or strips out of contactwith one another to remove the surface moisture to prevent them fromadhering to one another; e. finally drying said pieces or strips,immediately following the predrying to prevent diffusion of moisture totheir surface to a moisture content on the order of 71/2 percent; and f.reconstituting said pieces with water without loss of piece identity foruse in dish preparation.